Electrical properties of ultrathin titanium dioxide films on silicon

Abstract

Ultrathin (<50 nm) titanium dioxide (TiO2) films are being widely investigated as high-k dielectrics for future metal oxide semiconductor (MOS) technology. In this paper, ultrathin TiO2 films (∼20 nm) were deposited on silicon substrates by sputtering technique and subsequently annealed at 800 °C in oxygen environment for different durations (15–60 min). The annealed films were polycrystalline in nature with rutile phase. The value of dielectric constant was found to be 32–60 at 1 kHz measurement frequency. Threshold voltages of the MOS structures were found to vary from −0.1 to −0.5 V with the duration of annealing. Leakage current density (1 × 10−2–1 × 10−8 A/cm2 at 1 V) and dielectric breakdown fields (8.15–9.8 MV/cm) were observed to improve with annealing time.